Flexible or portable closure – partition – or panel – Plural strip – slat – or panel type – Venetian blind type
Reexamination Certificate
1999-01-13
2001-09-04
Purol, David M. (Department: 3634)
Flexible or portable closure, partition, or panel
Plural strip, slat, or panel type
Venetian blind type
C160S084040, C185S039000, C185S045000
Reexamination Certificate
active
06283192
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to flat spring drives or motors, which are useful in numerous applications and, in particular, relates to the application of such flat spring drives in window cover systems.
2. Definitions and Applicability
Typically, as used here, “cover” refers to expandable or extendible structures. These include slat structures such as so-called venetian or slat blinds and so-called mini-blinds. These structures also include pleated folding structures such as single and plural pleat structures and box, hollow and cellular structures. “Cover” also refers to fla g, sheet-type covers such as roller blinds. In this document, “cover” and “blind” are frequently used interchangeably. As applied to such covers, “operate” refers to the process of closing and opening the covers, typically (for horizontal covers) to lowering and raising the cover.
As used here, “horizontal” window cover refers to horizontally oriented covers such as horizontal slat blinds, horizontal folded pleat blinds and horizontal cellular blinds. The present invention is applicable generally to horizontal window cover systems and to flat window cover systems. It is understood that “window,” as used for example in “window cover,” includes windows, doorways, openings in general and even non-opening areas or regions to which covers are applied for decoration, display, etc.
As used here, the terms “operatively connected,” “operatively coupled,” “operatively connected or coupled” and the like include both direct connections of one component to another without intervening components and connections via intervening components including gears, transmissions, etc.
3. Current State of the Relevant Field
Typically a horizontal cover or blind is mounted above the window or space which is to be covered, and is operated using lift cords to extend the cover and lower it across the area, stopping at a selected position at which the blind partially or fully covers the area. For most horizontal slat blinds, the lift cords are attached to a bottom rail and the “rungs” or cross-members of a separate cord ladder are positioned beneath the slats of the blind. When the blind is fully lowered, each slat is supported by a rung of the blind's cord ladder and relatively little weight is supported by the lift cords. However, as the blind is raised, the slats are “collected” on the bottom rail, and the support of the slats is thus increasingly transferred from the cord ladder to the bottom rail and the weight supported by the rail and the lift cords increases.
Many pleated, cellular, box, etc., blinds are formed of resilient material having inherent spring-like characteristics. As the resilient pleated blind is raised toward the fully open position, the blind material is increasingly compressed, and requires increasingly greater force to overcome the compression force and move the blind and hold the blind in position. Effectively, then, both the slat blind and the pleated blind require increasingly greater force to open the blind and to maintain the blind open than is required to close the blind and maintain the blind closed.
The operating characteristics of conventional constant torque flat spring drives, especially long blinds, make it difficult to assist the opening and closing operation of horizontal and flat blinds. As applied to downward-closing embodiments of such blinds, spring drives usually are mounted at the top of the blind, and are operatively connected or coupled to the shaft about which the blind lift cords are wound. As described above, as the blind is lowered, the slat weight supported by the lift cords decreases and the compression of the pleats decreases. However, the torque force of the spring remains relatively constant, with the result that the spring torque may overcome the decreasing supported weight or the decreasing compression force, and raise the blind in fast, uncontrolled fashion. Also, it may be difficult to keep the blind at a selected position. Furthermore, if the blind is heavy, and requires a strong spring to maintain the blind open, the blind is particularly susceptible to instability and uncontrolled raising operation when partially or fully closed.
SUMMARY OF THE INVENTION
In one embodiment, the present invention is embodied in a spring drive which comprises a storage drum or spool, an output drum or spool, and a flat spring wound on the two drums or spools. In a preferred embodiment, the flat spring is adapted for providing a torque which varies along al least a section of the length of the spring. In a specific embodiment, at least one section of the spring has a cove of selected curvature which varies along the length of the spring for providing torque which varies proportional to the cove as the spring winds and unwinds. In another specific embodiment, at least one section of the spring has holes of selected size and location along the spring axis for providing torque which varies indirectly proportional to the transverse size of the holes and the resulting effective width of the spring as the spring winds and unwinds.
In another embodiment, the present invention is embodied in a plural spring drive system comprising an output drum; and a plurality of storage drums, each having a flat spring wound thereon. The plurality of flat springs extend to and are wound together in overlapping fashion on the output drum, such that the system torque at the output drum is a multiple of the torques associated with the individual flat springs. Various alternative arrangements can be used, for example, the storage drums can be arranged in approximately a straight line; the output drum and the storage drums can be arranged in approximately a straight line; the storage drums can be arranged in a cluster; and the output drum and the storage drums can be arranged in a cluster. In a preferred embodiment, at least one of the flat springs is adapted for imparting a torque component to the system torque which varies along the length of the said one spring. In one specific embodiment, the said one spring has a cove or transverse curvature which selectively varies along the length of the said spring for providing torque which varies proportional to the transverse curvature of the said spring at a position closely adjacent the output drum as the said spring winds and unwinds. In another specific embodiment, the said one spring has holes along its length for providing torque which varies proportional to the transverse size of the holes and the resulting effective width of the said spring when one or more holes is positioned closely adjacent the output drum as the spring winds and unwinds.
In another embodiment, the spring drive further comprises a magnetic brake comprising one or more magnetizable regions or magnets at selected positions along the flat spring, or at least one of the flat springs; and a magnet brake member mounted adjacent the flat spring, so the brake member stops the flat spring at the selected positions.
In yet another embodiment, the spring drive further comprises a detent brake comprising one or more holes at selected positions along the flat spring, or at least one of the flat springs; and a detent brake member biased against the flat spring for engaging the holes and stopping the flat spring at the selected positions.
Other embodiments of spring drives in accordance with the present invention include constant cove section(s); and/or sections selected from varying cove(s), including reverse curvature cove(s); and/or perforated section(s).
Still additional specific embodiments of the present invention include individual spring drives comprising plural springs, and spring drive systems comprising plural spring drive units, including individual spring drive units which comprise single or plural springs.
The present invention is also embodied in window cover systems which include one or more spring drives of the type described herein.
Additionally, the present invention is embodied in spring drives and spring drive cover system
Dalton Philip A.
Purol David M.
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